For this code:

   a = IntegerExponent[k,7]; (*a is highest power of 7 that divides k*)

I would like to find b, where b is:

   b = IntegerPower[k,7]; (*b is highest power of 7 that is less than k*)

Is there an efficient way to implement a function to do that?

cheers, Jamie


1 Answer 1

IntegerPower[k_, b_] := If[IntegerQ[#], # - 1, Floor[#]] &@Rationalize[Log[b, k]];


IntegerPower[345, 7] (* Outputs 3 *)
IntegerPower[0.0028, 7] (* Outputs -4 *)
IntegerPower[100, 2] (* Outputs 6 *)
IntegerPower[0.5, 2] (* Outputs -2 *)
  • $\begingroup$ Imo this function is a candidate for the Wolfram Function Repository. Although modified to (b is highest power of 7 that is less than =or equal= to k). As it is quite often used. $\endgroup$ Commented Jun 20, 2023 at 13:24

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